Subscriptions

Push semantics. Subscribe to your subgraph table writes — the server delivers signed webhooks.

A subscription binds to a subgraph table. Every row your handler writes that matches the filter triggers a signed HTTP POST to your endpoint, with automatic retries and idempotency keys.

Create a subscription

sl subscriptions create \
  --subgraph sbtc-flows \
  --table transfers \
  --url https://your-app.com/webhooks/sbtc

Verify the signature

Every delivery is signed. Verify the secondlayer-signature header against your subscription secret before trusting the payload.

import { verifyWebhookSignature } from "@secondlayer/sdk";

const valid = verifyWebhookSignature(req.headers, rawBody, secret);
if (!valid) return new Response("bad signature", { status: 401 });

Failed deliveries retry with backoff; after repeated failures the subscription's circuit opens so a downed endpoint can't block the queue.